CCAMLR

Fishing in the Amundsen Sea region (SSRUs 882C–H) has been managed through a research plan since the 2015 fishing season. The aim of the research plan is to collect sufficient information to carry out a reliable stock assessment of the toothfish stock in that area. In this report, we assess if the research plan is thus far achieving its goals and if the current fishing level is deemed precautionary.

In the 2016 and 2017 seasons, a total of 19 tagged fish (excluding within season recaptures) were recaptured in the research blocks in the South Amundsen Sea region, confirming the utility of the research plan to recapture tagged fish, and providing key information on the size of the population in the South. Although only 4 tagged fish were recaptured (excluding within season recaptures) in the North (SSRU 882H) in 2017, the increase in tagging rate to 3 fish per tonne in the 2017 season has increased the number of tagged fish at liberty and therefore the number of recaptures of tagged fish is likely to increase in the 2018 season.

Catch rates, length frequency data, access to research blocks and Chapman biomass estimates for the North and South areas all indicate that the current catch limits in the Amundsen Sea region are precautionary and we recommend extending the current research plan for 2018 season.

No validated age data are currently available since 2014 for the North, and for 2014, 2015, and 2017 from the South to support the development of a stock assessment.

We provide extensive diagnostic plots for the 2017 models R1 and R3 for Antarctic toothfish in the Ross Sea as recommended by WG-SAM-15 (2015). The stock assessment rationale and models as well as their main diagnostics are described in Mormede (2017). The CASAL files for the assessment models were provided to the CCAMLR Secretariat as a zip file.

In this paper we present the results for first inputs, model R1 and then model R3. The diagnostic plots cover input data, MPD and MCMC outputs. Key tables are given in Mormede et al. (2017) including process error weightings and the MPD objective function components.

We provide a summary of the mark-recapture data inputs to the 2017 Ross Sea region stock assessment.

A total of 44 827 Antarctic toothfish have been released and 2473 recaptured, and 1 191 Patagonian toothfish released and 103 recaptured since 2001. Effective tagging survival and tag detection rates for each vessel were calculated. In the last few years the effective tagging survival is estimated at about 65% and the effective tag detection rate at about 85%.

Ukraine proposes a plan for scientific research in Statistical Subarea 88.1 for vessels SIMEIZ, KOREIZ, CALIPSO and MARIGOLDS based on the provisions of paragraph 2 of Conservation Measure 91-05. Studies are expected to be conducted in the Special Research Zone.

The research of Dissostichus in Subarea 88.3 carried out by Chile in 1998, New Zealand in 2005, Russia in 2011 and 2012 and the Republic of Korea in 2016. It was noted that no tagged fishes were recaptured during the previous research activities. Studies are planned to be conducted from January to April, as ice conditions permit. It is planned that the number of longline sets will be 60 in four reserch blocks. It is planned to complete the study for Dissostichus spp. in Subarea 88.3 within 3 years.

Ukraine proposes to conduct survey in three research blocks in Division 58.4.2 during the season 2017/18. 

Ukraine proposes to carry out a scientific survey of Dissostichus spp. by bottom longline in the eastern part of Subarea 48.1.

The third year research survey of Ukraine in Subarea 48.2 by the fishing vessel SIMEIZ is finished. Ukraine proposes to continue survey in same boundary for the next 2 year.

The Scientific Committee has previously considered results from the Krill-Predator-Fishery Model to assess the risks of distributing catch limits for krill among small-scale management units (SSMUs) in Subareas 48.1, 48.2, and 48.3. Here we describe a method to update the parameterizations of this model and conduct comparable risk assessments at smaller spatial scales. We use the method to assess some of the risks associated with two marine protected area (MPA) scenarios in Planning Domain 1, one representing the MPA proposed by Argentina and Chile. We conclude that the MPA proposed by Argentina and Chile can, if desired, be improved by changing the sizes of the coastal buffers that define the General Protection Zones around the South Shetland and South Orkney Islands. We also conclude that the proposed MPA seems likely to satisfy multiple objectives simultaneously.

In order to explore aspects related to the structure of population units and habitat use of Dissostichus spp. within CCAMLR Subarea 48.2, the elemental composition of nuclear and marginal sections of 10 otoliths from adults of D. eleginoides and 20 otoliths from adults of D. mawsoni from samples of otoliths collected during the first season of the research carried out by the Chilean Delegation in Subarea 48.2 of CCAMLR during the 2015/16 fishing season. The otoliths through laser ablation and mass spectrometry with inductively coupled plasma (LA-ICPMS) was sampled and analyzed. Eleven elements were selected for analysis: 7Li, 23Na, 24Mg, 52Cr, 55Mn, 59Co, 60Ni, 63Cu, 86Sr, 120Sn y 138Ba, using their relative concentration to Ca. The univariate and multivariate analysis of the elemental composition of the nuclear zone showed significant differences between species, suggesting physiological differences and/or segregation of nursery habitats between them. The analysis of the elemental composition of the marginal sections presented univariate differences but not multivariate differences between species, suggesting a higher degree of overlap between the habitats used by the adults of each one of them. The differences found between nuclear and marginal sections among the species were consistent with the change of habitats described in the literature for each one of them. The comparison of our results with previous reports of elemental composition showed similarity between D. eleginoides samples of this study and the samples previously collected in South Georgia and Shag Rocks. In the case of D. mawsoni, the results clear differ from the results available for the Ross Sea, suggesting the existence of different demographic and/or evolutionary units in each area.